Effects of Chemical Application on Antifouling in Steam-Assisted Gravity Drainage Operations

Abstract

The fouling behavior of water streams in steam-assisted gravity drainage (SAGD) operations can be affected by chemical selection, including a reverse emulsion breaker, demulsifier, flocculant, and dispersant. Reverse emulsion breakers and demulsifiers were chosen to give the cleanest water quality and best dehydration during laboratory testing of reverse emulsions produced at SAGD facilities. A group of polyquaternary amine reverse emulsion breakers were synthesized to have a range of molecular weights with equivalent charge densities. The effect of their molecular weights on water clarification was investigated by standard bottle testing. It was found that the higher the molecular weight, the more effective the chemical was at removing suspected fouling agents. A flocculant has to be used with care to avoid overtreatment of the system. If fouling occurs during normal operation due to produced water from the primary separation vessel containing residual amounts of oil or other impurities, remediation can be used to address the fouling. A series of dispersants were tested to check if the oil could be kinetically stabilized in the produced water phase. It was shown that decreased viscosity of the oil increased the tendency for the oil to be dispersed. Certain surfactants helped the oil to be dispersed into the water and then to be released upon settling for 30 min. This type of dispersant could be applied in any SAGD operation with heat exchanger fouling problems.